Ballcock valves for use in water storage tanks uniformly have the function of opening to supply water to the tank when the water is below a desired storage level, and closing while the water is at or above the desired storage level. Because their operation is related to the water level as it exists in the tank, these valves include a float. The float is somehow connected to the workings of the valve, usually through a pivoted lever.
Such valves are well-known to generations of people who have installed and replaced them, or have had them serviced. Perhaps the most familiar type is shown in Antunez Jr. U.S. Pat. No. 3,070,118, which is a plug-type valve that is opened and closed as the float lowers and rises.
There is another popular type of valve which operates on a differential-pressure principle. This type is exemplified by Roosa U.S. Pat. No. 4,922,556. In such a valve the opening and closing of a vent port reduces or increases the differential pressure across a diaphragm which in turn opens or closes the valve to flow. When the float moves up and down, its position determines whether the vent port is opened or closed.
There are considerable advantages to the pressure-differential type of valve. For example, their actions are usually smoother than the plug-type valves, and the mechanical force needed to operate them is much less than that required for plug-type valves.
Of even greater importance is that the differential-pressure type valve user the system water pressure to keep the valve closed. The plug-type valve must oppose the system pressure by the exertion of a physical lever-type force exerted by the float arm. The use of system pressures for closure requires less linkage, and is potentially more reliable than the plug-type.
A disadvantage of known differential-pressure valves is the difficulty of servicing them. They constitute more than a mere plug to close an orifice. Furthermore, to the householder who has only an occasional (and hopefully very seldom) contact with these valves most of them look different. Given a choice, especially in the after-market-hardware and home supply stores--the purchaser inherently tends to prefer a valve which looks familiar.
As to the problem of servicing. It is at least a sales advantage to provide parts which can foreseeably be required to be replaced in a cartridge form that can quickly and easily be removed and replaced.
The manufacture of ballcock valves is very competitive. These valves sell in the millions each month, both for installation in new housing and offices, and for replacement in existing housing and offices. Increments of cost in fractions of a cent can lose substantial orders. Accordingly, if one wishes to sell differential-pressure type valves in major quantities, they must be cost-competitive with plug-type valves, and with other differential-type valves.
One way to be competitive is to be able to make the total valve out of long-tested, already tooled up basic parts, substituting only a few parts of the workings with different parts and perhaps an insert or two in the basic tool. A further advantage of this approach is that the resulting valve will look like a conventional ballcock.
This invention, by its compatibility with existing plug-type valve structures, enables a purchaser to buy and install a differential-pressure type workings in place of the plug-type workings. Thus at repair time he has the opportunity to change the type of his system.
It is an object of this invention to provide a pressure-differential ballcock valve whose workings can be accommodated in a nearly-standard ballcock body of the plug type, with an appearance closely simulative of already-known types. Preferably the workings will be provided as a plug-in unit.
It is yet another object of this invention to provide an anti-siphon system in which the siphon-breaking device never passes water, and which is disposed at the very top of the valve body, which is readily installed along with the plug in a unit, which does not undergo stretching in operation.
As a consequence of the foregoing, much existing tooling can be used to make a valve with only minor changes to accommodate the valve workings. Important economies are thereby available, and important sales advantages are presented.